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Unformatted text preview: BICD 100, Summer 2007 Second Midterm Exam Enter each answer into the appropriate box on the answer sheet. Turn in only the answer sheet. You may use
scratch paper, but you may not turn it in. 1 developing germ cells, which division produces the haploid state? a) the premeiotic mitosis b) meiosis I
eiosis l] d) the post meiotic mitosis e) some other division 2. If nondisjunction of the sex chromosomes in humans occurs only in males and only at the ﬁrst meiotic division,
what will be the ratio of XXX to XXY to XYY among newborns? @O: l :0 b) 1:2:1 c) 1:0:1 d) 0:1:1
e) 2:1:0 i) 1:3:0 g) some other ratio r 3. If nondisjunction of the Sex chromosomes in humans occurs equally in males and females, but only at the ﬁrst
meiotic divi ion, what will be the ratio of XXX to XXY to XYY? a) 0:1:0 b) 1:2:1 c) 1:0:1 d) 0:1:1
e) 221:0 1:3:0 g) some other ratio 4. If nondisjunction of the sex chromosomes in humans occurs only in males, but equally often in both meiotic
divisions, what will be the ratio ofXXX to XXY to XYY? a) 0:1:0 @133 c) 1:0:1 d) 0:1:1 e) 2:11)
t) 123:0 g) some other ratio 5. The ﬁgure at left shows the sex chromosomes of a human mother and father. One of them
has a chromosomal abnormality. Which one is it? a) mother ther c) impossible to
tell without being told which chromosomes belong to which parent (1) impossible to tell without being told what normal chromosomes look like 6. The term for this type of abnormality is a) reciprocal translocation b) deletion @pericenu’ic inversion d) paracenlric inversion e) Robertsonian translocation
impossible to tell for same reason as in #5 g) impossible to tell for a different reason 7 (2 pts). Parents with this array of chromosomes are at risk for a) infertility
b) abnormal oﬁ'spring c) elevated rates of nondisjunction d) elevated rates of mutation @no special risk 0 impossible to tell 8. The parent with the abnormality in the couple above would have anaphase bridges in
meiosis. T or 9. The chromosomes of the parent with the abnormality in the couple above would form a quadrivalent in meiosis.
T or . 10 (2 pts). If a woman happened to be heterozygous for the abnormality seen in one member of the couple above,
she would be at risk for a) infertility abnormal offspring c) elevated rates of nondisjunction d) elevated
rates of mutation e) no special risk 0 possible to tell 11. Such a woman would have anaphase bridges in meiosis. T or G 12 (2 pts). If a woman happened to be h zygons for the abnormality in the couple above, that person would be at
the same type of risk as the man in #7. or F 13 (2 pts) Imagine the ABO blood group locus is very near the centromere of chromosome 7. A man with type AB
blood is heterozygous for a reciprocal translocation between chromosomes 7 and 11. His wife has type 0 blood.
They produce a child with type AB blood. The sperm which this child received arose by a) alternate segregation
b) adjacent I segregation @adjacent II segregation d) crossing over in the loop e) some other mechanism
0 impossible to tell l4 (2 pts). Colorblindness is X-linked in humans. If the frequency of the colorblindness allele is 0.1, what is the
probability of a mating between a colorblind man and a colorblind woman in a random mating population? (Write answer in box 12 of answer sheet) 15. Boys with Klinefelter syndrome are colorblind at the same rate as chromosomally normal boys. T or E) 16. Boys with the 47,XYY karyotype are colorblind at the same rate as normal boys. (I) or F <7" In Drosophila, the mutant B causes bar-shaped eyes, y causes yellow body, and w causes white eyes. A yellow bodied white eyed male with bar eyes was mated to a wildgzpefemale homozygous at all three loci. 0f the F1
oﬂfrpring 39 were wildtype and 40 had bar eyes. There was no sex (inference. When the bar eyed F 1 females were
mated to wild I: e F1 males, the following oﬁspring were obtained (only mutant traits are mentioned) m
wild ‘ - e female
bar female yellow, white bar male
yellow, white 46
male 45
J1. h “(40 22. w and B are linked to each other. T or @ 17. Which locus or loci is or are X-linked? a) yellow only b) white only 0) bar
only @yellow and white e) yellow and bar D White and bar g) all three
h) none i) X—linkage cannot be determined from the information given 101 18.yandwarelinkedtoeachother. @ or F 19. y and w are a) 0 @5 c) 10 d) 20 e) some other number map units
apart 20. y and B are linked to each other. T or @ 21.yandBare a)0 b)5 c)10 d)20 omeothernumber mapunits
apart. " 23. w and B are a) 0 b) 5 c) 10 d) 20 orne other number map units apart. - 24 When a child is born with Down Syndrome, the risk of Down Syndrome in the next child is a) the same as for
any other child of the same age mother b) reduced because it is unlikely to have two Downs in the same family
‘ creased, because one parent might be a balanced heterozygote for a Robertsonian translocation involving
omosome 21 d) increased because one parent might be a balanced heterozygote for a pericentric inversion
involving chromosome 21 e) increased because nondisjunction runs in families ' ~—-—- 25. ' increasing maternal age increases the odds of a genetic defect in the child, increasing paternal age does not. or F 26 (2 pts). The cells of mammalian females contain twice as much gene product ﬁ'om most X-linked genes as the
cells of mammalian males. CW or F Imagine that in hamsters only the genotype aabb confers rough coat. HavingA or B or both makes the coat smooth
The a and b loci are linked, 20 mu apart 27. An AABB male was crossed to an aabb female, and an F1 male was backcrossed to the a b female. What
proportion of the offspring should be rough? a) .01 b) .04 c) .0625 d) .1 e) .25 4 g) .5 h) some other number 28. An AAbb male was crossed to an aaBB female, and an F1 female was then crossed to an aabb male. What
pr0portion of the offspring should be rough? a) .01 b) .04 c) .0625 .l e) .25 t) .4 g) .5 h) some
other number 29 (2 pts). The F1 female from the cross in #28 was crossed to an F1 male ﬁ'om the same cross. What proportion of
the offspring should be rough? .01 b) .04 c) .0625 d) .l e) .25 t) .4 g) .5 h) some other number 30 (2 pts). The F1 female from the cross in 28 was crossed to an F1 male from the cross in #27. What proportion of
the offspring should be rough? a) .01 .04 c) .0625 d) .l e) .25 t) .4 g) .5 h) some other number 31. a will be linked to b is cis heterozygotes, but not in trans heterozygotes. T or In a variety of weed the R allele produces red ﬂowers while rr ﬂowers are white. The S allele produces large ﬂowers, while ss ﬂowers are small. The allele 0 produces scented ﬂowers, while 00 ﬂowers are odorless. A cross was made between a plant with large red scented ﬂowers and a plant with small
white odorless ﬂowers, and the following progeny were obtained
[-
[—
[-
Ii-
[13-- 33. How many of the loci are linked to each other? a) none b) l c) 2 @3 e) can’t tell 32. There are more large white scented progeny than large white odorless ones
because a) large white scented i lants are non recombinants while large white odorless are single crossovers arge white scented plants are single
crossovers while large white odor ess are double crossovers c) both are single
crossovers, but the crossover in the large white scenteds occurred in a larger
interval d) the difference is just a random deviation from expected e) impossible to tell 34. R and S were in coupling in the red parent. @ or F 35 (8 pts). Draw a map of the three loci. Place the map in box 35 on the answer sheet. ...
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